In conventional single-shaft solar trackers, a plurality of posts for supporting solar modules are installed upright on the ground. Rotatably supported by the posts, a single rotating shaft is provided. The solar modules are integrally supported on an upper end of the rotating shaft.
The solar modules are provided parallel to the ground. A controller rotates the rotating shaft relative to the posts and makes the solar modules face the sun from sunrise to sunset so that the light of the sun enter the solar modules at an angle as close to perpendicular to the solar modules as possible.
However, for the solar modules provided parallel to the ground, although the angle of incidence at which the light of the sun enters the solar modules is relatively close to the desired 90 degree angle in summer, the altitude of the sun in winter is lower than that in summer and the angle of incidence of the sun light is thus significantly far from the desired 90 degree angle, therefore the efficiency of photovoltaic power generation is markedly reduced.
Typically, one or more solar modules are provided in the form of a group; although the number of solar modules is determined depending on a required amount of electricity. Here, a device for varying the orientation of a large, medium or small-sized group of solar modules according to the location of the sun is required.